The present invention relates to a conveyor of the type composed of an endless chain and carriers attached to the chain at uniform intervals, in which the chain forms a loop of adjustable length while the carriers do not follow the loop, so that when a change is made in the spacing between the carriers the effective length of the chain, excluding the loop, can be set to a whole number multiple of this spacing.
A conveying device of this type which is described in Swiss Pat. No. 412,708 and corresponding British Pat. No. 1,060,219 has the advantage that the carrier spacing can easily be adapted to change in type or size, respectively, of the objects to be conveyed, for example a series of cookies to be packaged. In this known device, the carriers have a length which enables them to bridge the space between the beginning and end of the loop and are provided with two longitudinally spaced pairs of teeth which are in engagement with the chain, and the chain is a triple-strand roller chain. During the bridging, one pair of teeth engages the chain on the downstream side to the loop, with the result that the return sprockets over which the chain is guided, at which time the length of the carrier which corresponds to two or more chain link lengths becomes tangential to the sprockets must have a large diameter. However, this is known to be a severe drawback, particularly in connection with packaging machines, for the connection of elements such as a feeder chain, folding box, transversal heating device, removal chain and the like which precede or follow the conveyor, since it may lead to complicated structures or malfunctions during operation.